Semiconductor device including conductive structure having nucleation structure and method of forming the same

ABSTRACT

A semiconductor device and a method of forming the same, the semiconductor device including an insulating structure having an opening; a conductive pattern disposed in the opening; a barrier structure covering a bottom surface of the conductive pattern, the barrier structure extending between the conductive pattern and side walls of the opening; and a nucleation structure disposed between the conductive pattern and the barrier structure. The nucleation structure includes a first nucleation layer that contacts the barrier structure, and a second nucleation layer that contacts the conductive pattern, and a top end portion of the second nucleation layer is higher than a top end portion of the first nucleation layer.

CROSS-REFERENCE TO RELATED APPLICATION

This is a Continuation of U.S. application Ser. No. 16/441,433, filedJun. 14, 2019, which is a Continuation of U.S. application Ser. No.15/806,527, filed Nov. 8, 2017, in which a claim of priority is made toKorean Patent Application No. 10-2017-0011965, filed on Jan. 25, 2017 inthe Korean Intellectual Property Office, the entire contents of whichare hereby incorporated by reference.

BACKGROUND

The present inventive concept relates to a semiconductor device and amethod of forming a semiconductor device and, more particularly, to asemiconductor device including a conductive structure having anucleation structure and a method of forming a semiconductor deviceincluding the aforementioned conductive structure.

With the recent trend of increasing integration in semiconductordevices, the size of elements configuring semiconductor devices has beenreduced. For example, the size of elements formed of a metallicmaterial, such as contact plugs for example, has been reduced. However,as contact plugs have been reduced in size, small defects that may occurtherein are increasingly affecting the performance or operatingcharacteristics of semiconductor devices.

SUMMARY

Embodiments of the inventive concept provide a semiconductor deviceincluding a conductive structure which may reduce the occurrence ofdefects.

Embodiments of the inventive concept may provide a semiconductor deviceincluding a conductive structure that may improve electricalcharacteristics.

Embodiments of the inventive concept provide a semiconductor deviceincluding an insulating structure having an opening; a conductivepattern disposed in the opening; a barrier structure extending betweenthe conductive pattern and side walls of the opening, the barrierstructure covering a bottom surface of the conductive pattern; and anucleation structure disposed between the conductive pattern and thebarrier structure. The nucleation structure includes a first nucleationlayer that contacts the barrier structure, and a second nucleation layerthat contacts the conductive pattern, and a top end portion of thesecond nucleation layer is above a top end portion of the firstnucleation layer.

Embodiments of the inventive concept provide a semiconductor deviceincluding a first insulating structure having an opening; and a firstconductive structure disposed in the opening. The first conductivestructure includes a barrier structure, a nucleation structure, and aconductive pattern. The barrier structure and the nucleation structureextend between the conductive pattern and the first insulatingstructure, the barrier structure covering a bottom surface of theconductive pattern. The nucleation structure is disposed between thebarrier structure and the conductive pattern. The nucleation structureincludes a first impurity element. The nucleation structure includes afirst nucleation layer that contacts the barrier structure, and a secondnucleation layer that contacts the conductive pattern. A concentrationof the first impurity element in the first nucleation layer is higherthan a concentration of the first impurity element in the secondnucleation layer.

Embodiments of the present inventive concept provide a method of forminga semiconductor device including forming a barrier material layer;forming a nucleation material layer on the barrier material layer; andforming a conductive material layer on the nucleation material layer.The nucleation material layer is formed by performing a depositionprocess using a first reducing material, a second reducing material, anda source material. A Gibbs free energy of the first reducing materialwith respect to the source material is lower than a Gibbs free energy ofthe second reducing material with respect to the source material. Theforming of the nucleation material layer includes an initial unitprocess of forming a first nucleation material that contacts the barriermaterial layer, and a final unit process of forming a second nucleationmaterial that contacts the conductive material layer. The initial unitprocess includes supplying the first reducing material and the sourcematerial to a process chamber sequentially. The final unit processincludes supplying the second reducing material and the source materialto the process chamber sequentially.

Embodiments of the inventive concept provide a method of forming asemiconductor device including forming a barrier material layer; forminga nucleation material layer on the barrier material layer; and forming aconductive material layer on the nucleation material layer. Thenucleation material layer is formed by performing a first depositionprocess using a first reducing material, a second reducing material, anda source material. The forming of the nucleation material layer includesan initial unit process of forming a first nucleation material that isamorphous and that contacts the barrier material layer, and a final unitprocess of forming a second nucleation material that is crystalline andthat contacts the conductive material layer. The initial unit processincludes supplying the first reducing material and the source materialto a process chamber sequentially. The final unit process includessupplying the second reducing material and the source material to theprocess chamber sequentially.

Embodiments of the inventive concept further provide a semiconductordevice including a device isolation region disposed on a substrate, thedevice isolation region defining active regions; a gate disposed overthe active regions; gate insulating spacers covering side walls of thegate; and source/drain regions disposed on both sides of the gate overthe active regions. The gate includes a first conductive layer, a secondconductive layer and a third conductive layer. The third conductivelayer is disposed between the gate insulating spacers. The firstconductive layer covers lateral surfaces and a bottom surface of thethird conductive layer. The second conductive layer is disposed betweenthe first conductive layer and the third conductive layer. The secondconductive layer comprises a first nucleation layer contacting the firstconductive layer and a second nucleation layer contacting the thirdconductive layer. A top end portion of the second nucleation layer isabove a top end portion of the first nucleation layer.

Embodiments of the inventive concept further provide a semiconductordevice including an device isolation region defining active region; asource/drain region on the active region; and a contact plug on thesource/drain region. The contact plug includes a barrier structure, anucleation structure and a conductive pattern. The barrier structurecovers lateral surfaces and a bottom surface of the conductive pattern.The nucleation structure is disposed between the conductive pattern andthe barrier structure. The nucleation structure comprises a firstnucleation layer disposed between the conductive pattern and the barrierstructure, and a second nucleation layer disposed between the firstnucleation layer and the conductive pattern. A top end portion of thesecond nucleation layer is above a top end portion of the firstnucleation layer.

BRIEF DESCRIPTION OF DRAWINGS

The above, and other aspects, features, and advantages of the inventiveconcept will be more clearly understood from the following detaileddescription when taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 illustrates a cross-sectional view of a semiconductor deviceaccording to an example embodiment of the inventive concept;

FIG. 2 illustrates an enlarged view of part A of FIG. 1;

FIG. 3 illustrates an enlarged view of part C of FIG. 2;

FIG. 4 illustrates a graph schematically showing distributioncharacteristics of impurity elements in some components of asemiconductor device according to an example embodiment of the inventiveconcept;

FIG. 5A illustrates a cross-sectional view of a modified example of asemiconductor device according to an example embodiment of the inventiveconcept;

FIG. 5B illustrates a cross-sectional view of another modified exampleof a semiconductor device according to an example embodiment of theinventive concept;

FIG. 5C illustrates a cross-sectional view of another modified exampleof a semiconductor device according to an example embodiment of theinventive concept;

FIG. 5D illustrates a cross-sectional view of another modified exampleof a semiconductor device according to an example embodiment of theinventive concept;

FIG. 6 illustrates a perspective view of a semiconductor deviceaccording to an example embodiment of the inventive concept;

FIG. 7A illustrates a plan view of another modified example of asemiconductor device according to an example embodiment of the inventiveconcept;

FIG. 7B illustrates a cross-sectional view of a region taken along linesI-I′ and II-II′ of FIG. 7A;

FIG. 7C illustrates a cross-sectional view of a region taken along linesII-II′ of FIG. 7A;

FIG. 8A illustrates a plan view of another modified example of asemiconductor device according to an example embodiment of the inventiveconcept;

FIG. 8B illustrates a cross-sectional view of a region taken along linesIII-III′ of FIG. 8A;

FIG. 8C illustrates a cross-sectional view of a region taken along linesIV-IV′ of FIG. 8A;

FIG. 9 illustrates a flow chart of a method of forming a semiconductordevice according to an example embodiment of the inventive concept;

FIG. 10A illustrates a cross-sectional view of a method of forming asemiconductor device according to an example embodiment of the inventiveconcept;

FIG. 10B illustrates a further cross-sectional view of a method offorming a semiconductor device described with respect to FIG. 10A;

FIG. 10C illustrates a still further cross-sectional view of a method offorming a semiconductor device described with respect to FIG. 10A;

FIG. 11 illustrates a flow chart of a method of forming a semiconductordevice according to an example embodiment of the inventive concept;

FIG. 12A illustrates a gas pulsing diagram illustrating an example of amethod of forming a semiconductor device according to an exampleembodiment of the inventive concept;

FIG. 12B illustrates a gas pulsing diagram illustrating another exampleof a method of forming a semiconductor device according to an exampleembodiment of the inventive concept;

FIG. 12C illustrates a gas pulsing diagram illustrating another exampleof a method of forming a semiconductor device according to an exampleembodiment of the inventive concept;

FIG. 12D illustrates a gas pulsing diagram illustrating another exampleof a method of forming a semiconductor device according to an exampleembodiment of the inventive concept;

FIG. 12E illustrates a gas pulsing diagram illustrating another exampleof a method of forming a semiconductor device according to an exampleembodiment of the inventive concept; and

FIG. 12F illustrates a gas pulsing diagram illustrating another exampleof a method of forming a semiconductor device according to an exampleembodiment of the inventive concept.

DETAILED DESCRIPTION

A semiconductor device 1 according to an example embodiment of theinventive concept will be described with reference to FIG. 1. FIG. 1illustrates a cross-sectional view of the semiconductor device 1according to an example embodiment of the inventive concept.

Referring to FIG. 1, the semiconductor device 1 according to an exampleembodiment includes a substrate 10, an insulating structure 20, and aconductive structure 30.

The insulating structure 20 has an opening 21. The opening 21 of theinsulating structure 20 may pass through the insulating structure 20. Inan example embodiment, the opening 21 of the insulating structure 20 mayexpose a portion of the substrate 10. The insulating structure 20 may beformed of an insulating material such as for example a low-k dielectric,a silicon oxide, or a silicon nitride, or the like. The insulatingstructure 20 may include a single layer, but the inventive concept isnot limited thereto. For example, in other embodiments of the inventiveconcept the insulating structure 20 may include two or more insulatingmaterial layers.

The substrate 10 may include a variety of components thereon. Forexample, the substrate 10 may include a source/drain region of atransistor. Thus, the portion of the substrate 10 exposed by the opening21 of the insulating structure 20 may be the source/drain region.However, the inventive concept is not limited thereto. For example, thesubstrate 10 may include a well contact region for contact of a wellregion in the substrate 10, and the portion of the substrate 10 exposedby the opening 21 of the insulating structure 20 may be the well contactregion. Alternatively, the portion of the substrate 10 exposed by theopening 21 of the insulating structure 20 may be a conductive contactpad region for electrically connecting a channel region of a transistoror wirings.

The conductive structure 30 is disposed in the opening 21 of theinsulating structure 20. In an example embodiment, the conductivestructure 30 may fill the opening 21.

The conductive structure 30 includes a barrier structure 40, anucleation structure 50, and a conductive pattern 60.

The conductive pattern 60 may have a pillar shape. The barrier structure40 and the nucleation structure 50 extend between the conductive pattern60 and the insulating structure 20 while covering a bottom surface ofthe conductive pattern 60. The barrier structure 40 extends between theconductive pattern 60 and side walls of the opening 21. Moreparticularly, the barrier structure 40 extends between the nucleationstructure 50 and side walls of the opening 21. That is, the nucleationstructure 50 is disposed between the barrier structure 40 and theconductive pattern 60. The conductive pattern 60 may include for examplea bulk tungsten (W) material, formed using the nucleation structure 50as a seed.

A portion of a top surface of the conductive structure 30 may berecessed. The barrier structure 40 and the conductive pattern 60 mayhave coplanar top surfaces. At least a portion of a top surface 50 s ofthe nucleation structure 50 may be recessed. The at least a portion ofthe top surface 50 s of the nucleation structure 50 may be a stepped topsurface.

An example of the barrier structure 40 and the nucleation structure 50will be described with reference to FIG. 2. FIG. 2 illustrates anenlarged view of part A of FIG. 1.

Referring to FIGS. 1 and 2, the barrier structure 40 includes a firstbarrier layer 42 and a second barrier layer 44. The first barrier layer42 may contact the insulating structure 20. In an example embodiment,the first barrier layer 42 contacts the substrate 10. The second barrierlayer 44 is interposed between the nucleation structure 50 and the firstbarrier layer 42 and may contact the nucleation structure 50.

The first barrier layer 42 may be formed of a metallic material, and thesecond barrier layer 44 may be formed of a nitride of the metallicmaterial forming the first barrier layer 42. For example, the firstbarrier layer 42 may be formed of titanium (Ti), and the second barrierlayer 44 may be formed of titanium nitride (TiN).

The nucleation structure 50 includes a first nucleation layer 52 and asecond nucleation layer 58. The first nucleation layer 52 may contactthe barrier structure 40, and the second nucleation layer 58 may contactthe conductive pattern 60.

In an example embodiment, the thickness t1 of the first nucleation layer52 is greater than the thickness t2 of the second nucleation layer 58.

A top end portion 50 s 1 of the first nucleation layer 52 may berecessed further than a top end portion 50 s 2 of the second nucleationlayer 58. The top end portion 50 s 1 of the first nucleation layer 52may be lower than the top end portion 50 s 2 of the second nucleationlayer 58, and thus a height difference between the top end portion 50 s1 of the first nucleation layer 52 and the top end portion 50 s 2 of thesecond nucleation layer 58 may cause a step to be formed on the topsurface 50 s of the nucleation structure 50. In other words, the top endportion 50 s 2 of the second nucleation layer 58 is higher than (orabove) the top end portion 50 s 1 of the first nucleation layer 52. Inan example embodiment, the second nucleation layer 58 may protect theconductive pattern 60 while covering a lateral surface of the conductivepattern 60.

An example of a crystal structure of the nucleation structure 50 and theconductive pattern 60 will be described with reference to FIG. 3. FIG. 3illustrates an enlarged view of part C of FIG. 2.

Referring to FIG. 3, the second nucleation layer 58 and the conductivepattern 60 may have the crystal structure. That is, second nucleationlayer 58 and the conductive pattern 60 may be crystalline. The size ofgrains 50 g of the second nucleation layer 52 may be smaller than ofgrains 60 g of the conductive pattern 60. In an example embodiment, thefirst nucleation layer 52 may have an amorphous structure.

In an example embodiment, the nucleation structure 50 may be formed of anucleation material, including impurity elements. The nucleationstructure 50 that may be formed of the nucleation material, includingthe impurity elements, will be described with reference to FIGS. 1, 2,and 4.

FIG. 4 illustrates a graph schematically showing distributioncharacteristics of impurity elements in some components of thesemiconductor device 1 according to an example embodiment of theinventive concept.

Referring to FIGS. 1, 2, and 4, the nucleation structure 50 may beformed of the nucleation material including the impurity elements. In anexample embodiment, the nucleation material of the nucleation structure50 may be a tungsten (W) nucleation material. In the nucleationstructure 50, the first nucleation layer 52 may be formed of a firstnucleation material, and the second nucleation layer 58 may be formed ofa second nucleation material. The first and second nucleation materialsmay be tungsten (W) nucleation materials.

The first nucleation material of the first nucleation layer 52 may beformed using an atomic layer deposition (ALD) process, using a firstreducing material and a source material. The second nucleation materialof the second nucleation layer 58 may be formed using an ALD process,using a second reducing material different from the second reducingmaterial and the source material. The first reducing material may haveGibbs free energy with respect to the source material that is lower thanthat of a Gibbs free energy of the second reducing material with respectto the source material. For example, in an embodiment of the inventiveconcept the first reducing material may be B₂H₄ gas, the second reducingmaterial may be SiH₄ gas or GeH₄ gas, and the source material may be WF₆gas.

As described above, the first nucleation layer 52 formed of the firstnucleation material may contact the barrier structure 40, and the secondnucleation layer 58 formed of the second nucleation material may bespaced apart from the barrier structure 40, thereby significantlyreducing or preventing a volcano defect that may occur due to volatiletitanium fluoride (TiF₃). The volatile TiF₃ is formed by a reactionbetween F⁻ of the WF₆ gas used to form the nucleation structure 50, andtitanium (Ti) of the barrier structure 40 formed of a titanium(Ti)/titanium nitride (TiN) material. As understood in view of FIG. 3,the grains 60 g of the conductive pattern 60 have a grain size greaterthan a grain size of the grains 50 g of the second nucleation materialof the second nucleation layer 58.

In an example embodiment, there may remain a portion of elements, thatis a portion of the forming gases, used to form the first and secondnucleation layers 52 and 58 of the nucleation structure 50 using thefirst and second nucleation materials. For example, boron (B) of theB₂H₄ gas and fluorine (F) of the WF₆ gas in the nucleation structure 50may remain.

In this specification, boron (B) remaining in the nucleation structure50 is referred to as a “first impurity element,” and fluorine (F)remaining in the nucleation structure 50 is referred to as a “secondimpurity element.”

The conductive pattern 60 may include a bulk metal material, formedusing the nucleation structure 50 as a seed. The bulk metal materialincluded in the conductive pattern 60 may be formed using a chemicalvapor deposition (CVD) process, using a third reducing materialdifferent from the first and second reducing materials and the sourcematerial. The third reducing material may be H₂ gas, and the sourcematerial may be WF₆ gas.

FIG. 4 is a graph schematically illustrating distributioncharacteristics of the first and second impurity elements B and Fremaining in the nucleation structure 50 and the conductive pattern 60,when the first nucleation layer 52 is formed using an ALD process usingB₂H₄ gas as the first reducing material and WF₆ gas as the sourcematerial, the second nucleation layer 58 is formed using an ALD processusing SiH₄ gas as the second reducing material and WF₆ gas as the sourcematerial, and the conductive pattern 60 is formed using a CVD processusing H₂ gas as the third reducing material and WF₆ gas as the sourcematerial. In the graph of FIG. 4, the dotted line indicates thedistribution characteristics of the first impurity element B, and thesolid line indicates the distribution characteristics of the secondimpurity element F.

In the nucleation structure 50, the concentration of the first impurityelement B in the first nucleation layer 52 may be higher than theconcentration of the first impurity element B in the second nucleationlayer 58. In addition, in the nucleation structure 50, the concentrationof the second impurity element F in the second nucleation layer 58 maybe higher than the concentration of the second impurity element F in thefirst nucleation layer 52. Thus, the first nucleation material of thefirst nucleation layer 52 may have the first impurity element B in ahigher concentration than that of the first impurity element B in thesecond nucleation material of the second nucleation layer 58, and mayhave the second impurity element F in a lower concentration than that ofthe second impurity element F in the second nucleation material of thesecond nucleation layer 58. A portion of the nucleation structure 50adjacent to the barrier structure 40 may have the first impurity elementB in a higher concentration than that in a portion of the nucleationstructure 50 adjacent to the conductive pattern 60, and may have thesecond impurity element F in a lower concentration than that in theportion of the nucleation structure 50 adjacent to the conductivepattern 60.

The concentrations of the first and second impurity elements B and F inthe nucleation structure 50 may be higher than those in the conductivepattern 60.

In an example embodiment, the first nucleation material of the firstnucleation layer 52 may be less influenced by a material type orcharacteristic of the barrier structure 40 than the second nucleationmaterial of the second nucleation layer 58. Thus, the first nucleationlayer 52 may be deposited or formed on the barrier structure 40 to havea thickness that is more uniform than that of the second nucleationlayer 58. That is, although the second nucleation material is notdeposited on the barrier structure 40 and does not have a thickness thatis more uniform than that of the first nucleation material, the secondnucleation material is deposited on the first nucleation material tohave a uniform thickness. Thus, the second nucleation layer 58 may bedeposited or formed on the first nucleation layer 52 to have a uniformthickness. As a result, the nucleation structure 50 may be formed on thebarrier structure 40 to have a uniform thickness. As described withreference to FIG. 3, the first nucleation material of the firstnucleation layer 52 may have an amorphous structure, and the secondnucleation material of the second nucleation layer 58 may have a crystalstructure.

As described above, the first and second nucleation layers 52 and 58 maybe formed of first and second nucleation materials having differentcrystal structures and different deposition characteristics, and thusthe occurrence of defects in the conductive structure 30 may besuppressed. In addition, the first and second nucleation layers 52 and58 may increase electrical characteristics of the conductive structure30.

As described above, the nucleation structure 50 may include two layerssuch as the first and second nucleation layers 52 and 58, but theinventive concept is not limited thereto. For example, in otherembodiments of the inventive concept the nucleation structure 50 mayinclude one or more intermediate nucleation layers interposed betweenthe first nucleation layer 52 contacting the barrier structure 40, andthe second nucleation layer 58 contacting the conductive pattern 60.Examples of the nucleation structure 50 including the one or moreintermediate nucleation layers will be described with reference to FIGS.5A through 5D. FIGS. 5A to 5D are enlarged views of part A of FIG. 1,respectively.

FIG. 5A illustrates a cross-sectional view of a modified example ofsemiconductor device 1 according to an example embodiment of theinventive concept. Referring first to FIG. 5A, a nucleation structure 50includes a first nucleation layer 52 a contacting the barrier structure40, a second nucleation layer 58 contacting the conductive pattern 60,and intermediate nucleation layers 54 and 56 disposed between the firstand second nucleation layers 52 a and 58.

In this specification, the first nucleation layer 52 a is referred to asan “initial nucleation layer”, and the second nucleation layer 58 isreferred to as a “final nucleation layer”.

The intermediate nucleation layers 54 and 56 may include a firstintermediate nucleation layer 54 contacting the first nucleation layer52 a, and a second intermediate nucleation layer 56 contacting thesecond nucleation layer 58. In other words, the first intermediatenucleation layer 54 is disposed between the first nucleation layer 52 aand the second nucleation layer 58, and the second intermediatenucleation layer 56 is disposed between the first intermediatenucleation layer 54 and the second nucleation layer 58.

In an example embodiment, the first intermediate nucleation layer 54 maybe formed using an ALD process using the same reducing material andsource material as those in the second nucleation layer 58, and thesecond intermediate nucleation layer 56 may be formed using an ALDprocess using the same reducing material and source material as those inthe first nucleation layer 52 a. Thus, the first intermediate nucleationlayer 54 and the second nucleation layer 58 may include (be formed of) anucleation material having substantially the same crystal structure andcomposition (e.g., second nucleation material), and the secondintermediate nucleation layer 56 and the first nucleation layer 52 a mayinclude (be formed of) a nucleation material having substantially thesame crystal structure and composition (e.g., first nucleationmaterial). Thus, the second intermediate nucleation layer 56 and thefirst nucleation layer 52 a may be formed of the first nucleationmaterial as described with reference to FIGS. 1 through 4, and the firstintermediate nucleation layer 54 and the second nucleation layer 58 maybe formed of the second nucleation material as described with referenceto FIGS. 1 through 4. The first and second nucleation materials havebeen described above with reference to FIGS. 1 through 4, and thusdetailed descriptions thereof will be omitted.

In example embodiments similar as shown in FIG. 5A, the first nucleationlayer 52 a and the second intermediate nucleation layer 56 may havesubstantially the same thickness. However, the inventive concept is notlimited thereto, and a thickness of the first nucleation layer 52 a maybe different than a thickness of the second intermediate nucleationlayer 56.

For example, FIG. 5B illustrates a cross-sectional view of anothermodified example of semiconductor device 1 according to an exampleembodiment of the inventive concept. As illustrated in FIG. 5B, anucleation structure 50 includes the first nucleation layer 52 a, thefirst intermediate nucleation layer 54, a second intermediate nucleationlayer 56′ having an increased thickness compared to the thickness of thefirst nucleation layer 52 a, and the second nucleation layer 58. Thus,in FIG. 5B, a thickness of the second intermediate nucleation layer 56′is greater than a thickness of the first nucleation layer 52 a.

In example embodiments similar as shown in FIG. 5A, the secondnucleation layer 58 and the first intermediate nucleation layer 54 mayhave substantially the same thickness. However, the present inventiveconcept is not limited thereto, and a thickness of the second nucleationlayer 58 may be different than a thickness of the first intermediatenucleation layer 54.

For example, FIG. 5C illustrates a cross-sectional view of anothermodified example of semiconductor device 1 according to an exampleembodiment of the inventive concept. As illustrated in FIG. 5C, anucleation structure 50 includes the first nucleation layer 52 a, afirst intermediate nucleation layer 54′ having an increased thicknesscompared to the thickness of the second nucleation layer 58, the secondintermediate nucleation layer 56, and the second nucleation layer 58.Thus, in FIG. 5C, a thickness of the first intermediate nucleation layer54′ is greater than a thickness of the second nucleation layer 58.

In example embodiments similar as shown in FIG. 5A, the first nucleationlayer 52 a and the second intermediate nucleation layer 56 may havesubstantially the same thickness, and the second nucleation layer 58 andthe first intermediate nucleation layer 54 may have substantially thesame thickness. However, the present inventive concept is not limitedthereto, and a thickness of the first nucleation layer 52 a may bedifferent than a thickness of the second intermediate nucleation layer56, and a thickness of the second nucleation layer 58 may be differentthan a thickness of the first intermediate nucleation layer 54.

For example, FIG. 5D illustrates a cross-sectional view of anothermodified example of semiconductor device 1 according to an exampleembodiment of the inventive concept. As illustrated in FIG. 5D, anucleation structure 50 includes the first nucleation layer 52 a, afirst intermediate nucleation layer 54′ having an increased thickness ascompared with the second nucleation layer 58, a second intermediatenucleation layer 56′ having an increased thickness as compared to thefirst nucleation layer 52 a, and the second nucleation layer 58. In FIG.5D, a thickness of the first intermediate nucleation layer 54′ isgreater than a thickness of the second nucleation layer 58, and athickness of the second intermediate nucleation layer 56′ is greaterthan a thickness of the first nucleation layer 52 a.

In embodiments of the inventive concept, a thickness of the firstintermediate nucleation layer 54 (54′) may be different than a thicknessof the second intermediate nucleation layer 56 (56′). In embodiments ofthe inventive concept, at least one of the first intermediate nucleationlayer 54′ and the second intermediate nucleation layer 56′ is thickerthan at least one of the first nucleation layer 52 a and the secondnucleation layer 58.

The conductive structure 30 described above with reference to FIGS. 1through 5D may be a contact plug of a semiconductor device. However, theinventive concept is not limited thereto. For example, in someembodiments of the inventive concept the conductive structure 30 mayalso be a wiring or a gate electrode having a line shape. The conductivestructure 30 as described above may be used in a contact plug, a gateelectrode, or a wiring. An example of the conductive structure 30, asapplied to a contact plug or a gate electrode, will hereinafter bedescribed with reference to FIG. 6.

FIG. 6 illustrates a perspective view of a semiconductor device 100according to an example embodiment of the inventive concept.

Referring to FIG. 6, the semiconductor device 100 includes a deviceisolation region 120 disposed on a semiconductor substrate 110 to definefin active regions 115, a gate G disposed over and traversing across thefin active regions 115, source/drain regions 150 disposed on the finactive regions 115 on both sides of the gate G, contact plugs 230disposed on the source/drain regions 150, and an insulating structure350 disposed on the semiconductor substrate 110. The insulatingstructure 350 may cover the source/drain regions 150 and the gate G. Thecontact plugs 230 may contact the source/drain regions 150 while passingthrough the insulating structure 350, and may be electrically connectedto the source/drain regions 150.

The gate G and the source/drain regions 150 may configure a transistor.The gate G may include a gate dielectric 320 and a gate electrode 330.The gate dielectric 320 may cover lateral surfaces and a bottom surfaceof the gate electrode 330. The gate dielectric layer 320 may be formedof a silicon oxide or a high-k dielectric. Gate insulating spacers 305may be disposed on (or covering) lateral surfaces (or side walls) of thegate G. The gate G is disposed in the opening between the gateinsulating spacers 305.

In an example embodiment, the cross-sectional structure of the gateelectrode 330 in a width direction (an x-axis direction) may be the sameas that of one of the examples of the conductive structure 30 describedwith reference to FIGS. 1 through 5D. For example, the gate electrode330 may include a first conductive layer 41 corresponding to the barrierstructure 40, a second conductive layer 51 corresponding to thenucleation structure 50, and a third conductive layer 61 correspondingto the conductive pattern 60.

The cross-sectional structure of each of the contact plugs 230 may bethe same as that of one of the examples of the conductive structure 30,described with reference to FIGS. 1 through 5D. Thus, the contact plug230 may include the barrier structure 40, the nucleation structure 50,and the conductive pattern 60, described with reference to FIGS. 1through 5D.

As a result, the structure of the conductive structure 30 including thebarrier structure 40, the nucleation structure 50, and the conductivepattern 60 as described with reference to FIGS. 1 through 5D, may beapplied to a contact plug or a gate electrode. For example, in anembodiment of the inventive concept, the gate G may include theconductive pattern 60 disposed between the gate insulating spacers 305;the barrier structure 40 extending between the conductive pattern 60 andthe gate insulating spacers 305 with the barrier structure 40 covering abottom surface of the conductive pattern; and the nucleation structure50 disposed between the conductive pattern 60 and the barrier structure40. Similarly as described previously and as may be appreciated in viewof FIG. 2, the nucleation structure 50 may include a first nucleationlayer 52 contacting the barrier structure 40 and a second nucleationlayer 58 contacting the conductive pattern 60, and the top end portion50 s 2 of the second nucleation layer 58 may be above the top endportion 50 s 1 of the first nucleation layer 52.

The conductive structure 30, described above with reference to FIGS. 1through 5D, may be coupled or connected to other components of asemiconductor device to configure the semiconductor device. Examples ofthe semiconductor device, including the conductive structure 30 coupledor connected to other components of the semiconductor device asdescribed above, will be described with reference to FIGS. 7A, 7B, 7C,8A, 8B and 8C.

FIG. 7A illustrates a plan view of another modified example of asemiconductor device according to an example embodiment of the inventiveconcept. FIG. 7B illustrates a cross-sectional view of a region takenalong lines I-I′ of FIG. 7A. FIG. 7C illustrates a cross-sectional viewof a region taken along lines II-II′ of FIG. 7A. FIG. 8A illustrates aplan view of another modified example of a semiconductor deviceaccording to an example embodiment of the inventive concept. FIG. 8Billustrates a cross-sectional view of a region taken along linesIII-III′ of FIG. 8A. FIG. 8C illustrates a cross-sectional view of aregion taken along lines IV-IV′ of FIG. 8A.

Referring to FIGS. 7A, 7B and 7C, a first insulating structure 1020 anda first conductive structure 1030 passing through the first insulatingstructure 1020 are disposed on or over a substrate 1010. The substrate1010 may correspond to the substrate 10 described with reference toFIG. 1. A second insulating structure 1120 and a second conductivestructure 1130 passing through the second insulating structure 1120 maybe disposed on or over the first insulating structure 1020 and the firstconductive structure 1030.

The first conductive structure 1030 is disposed in an opening (firstopening) 1021 passing through the first insulating structure 1020. Thesecond conductive structure 1130 is disposed in an opening (secondopening) 1121 passing through the second insulating structure 1120. Atleast one of the first or second conductive structures 1030 or 1130 maybe formed as one of the conductive structures 30 described withreference to FIGS. 1 through 5D. For example, the at least one of thefirst or second conductive structure 1030 or 1130 may be formed as thebarrier structure 40, the nucleation structure 50, and the conductivepattern 60 described with reference to FIG. 1. Thus, at least a portionof a top surface 1050 s of the nucleation structure 50 of the firstconductive structure 1030, or at least a portion of a top surface 1150 sof the nucleation structure 50 of the second conductive structure 1130,may be top end portions 50 s 1 and 50 s 2 having different heights, asdescribed with reference to FIG. 2. The nucleation structure 50 and thetop end portions 50 s 1 and 50 s 2 thereof as mentioned above have beendescribed with reference to FIGS. 1 through 5D, and details thereof willbe hereafter omitted.

The second insulating structure 1120 may include a first insulatinglayer 1114 and a second insulating layer 1116 disposed on (or over) thefirst insulating layer 1114. A portion of a top surface of the firstconductive structure 1030 may contact the second conductive structure1130, and the remainder of the top surface of the first conductivestructure 1030 may contact the second insulating structure 1120, or moreparticularly may contact the first insulating layer 1114. That is, thesecond conductive structure 1130 contacts at least a portion of a topsurface of the first conductive structure 1030. The second insulatinglayer 1116 may have a thickness greater than a thickness of the firstinsulating layer 1114. The first insulating layer 1114 may for examplebe formed of a nitride-based insulating material, and the secondinsulating layer 1116 may be formed of an oxide-based insulatingmaterial. The first insulating layer 1114 may be an etch stop layer. Inother embodiments the first and second insulating layers 1114 and 1116may be formed of other materials.

Of the top surface 1050 s of the nucleation structure 50 of the firstconductive structure 1030, the top end portions 50 s 1 and 50 s 2 havingdifferent heights to form the stepped top surface may be covered by thefirst insulating layer 1114 of the second insulating structure 1120. Inthe top surface 1050 s of the nucleation structure 50 of the firstconductive structure 1030, a top surface or top end portion 50 s 3contacting the second conductive structure 1130 may be recessed furtherthan the top end portions 50 s 1 and 50 s 2 forming the stepped topsurface. Thus, in the top surface 1050 s of the nucleation structure 50of the first conductive structure 1030, the top end portion 50 s 3contacting the second conductive structure 1130 may be lower than thetop end portions 50 s 1 and 50 s 2 contacting the first insulating layer1114 of the second insulating structure 1120. Thus, as described withreference to FIGS. 1 through 5D, the barrier structure 40 and theconductive pattern 60 contacting the first insulating layer 1114 mayhave coplanar top surfaces, and a portion of the nucleation structure 50contacting the first insulating layer 1114 may have a stepped topsurface. Also, of the stepped top surface of the nucleation structure50, the top end portion 50 s 1 adjacent to the barrier structure 40 maybe recessed further than the top end portion 50 s 2 adjacent to theconductive pattern 60, and the top end portion 50 s 3 of the nucleationstructure 50 contacting the second conductive structure 1130 may have atop surface recessed further than the stepped top surface.

The first conductive structure 1030 may have a bar shape when viewed ona plane, and the second conductive structure 1130 may contact a portionof the first conductive structure 1030.

In an example embodiment such as described with respect to FIGS. 7A, 7Band 7C, the second conductive structure 1130 may be disposed so thatportions of the nucleation structure 50 and the conductive pattern 60 ofthe first conductive structure 1030 that contact a bottom surface(lowermost) surface of the second conductive structure 1130 are recessedas compared with portions of the nucleation structure 50 and theconductive pattern 60 of the first conductive structure 1030 that do notcontact the bottom surface of the second conductive structure 1130. Thebottom (lowermost) surface of the second conductive structure 1130 ashere described should be understood to mean the planar surface of thesecond conductive structure 1130 extending along the x and y directionsthat is in contact with the underlying first conductive structure 1030.

The inventive concept is not limited as described with respect to FIGS.7A, 7B and 7C. Modified examples of the first and second conductivestructures 1030 and 1130 will be described with reference to FIGS. 8A,8B and 8C. Here, only modified portions of the first and secondconductive structures 1030 and 1130 will be described, and correspondingsimilar structure previously described with reference to FIGS. 7A, 7Band 7C may be omitted from the following.

Referring to FIGS. 8A, 8B and 8C, the modified second conductivestructure 1130′ may be disposed so that portions of the barrierstructure 40, the nucleation structure 50, and the conductive pattern 60of the modified first conductive structure 1030′ that contact a bottom(lowermost) surface of the modified second conductive structure 1130′are recessed as compared with portions of the barrier structure 40, thenucleation structure 50, and the conductive pattern 60 of the modifiedfirst conductive structure 1030′ that do not contact the bottom surfaceof the second modified conductive structure 1130′. The bottom(lowermost) surface of the second modified conductive structure 1130′ ashere described should be understood to mean the planar surface of thesecond modified conductive structure 1130′ extending along the x and ydirections that is in contact with the underlying modified firstconductive structure 1030′.

Examples of a method of forming a semiconductor device according toembodiment of the inventive concept will be described as follows. As anexample, a method of forming the semiconductor device 1 shown in FIG. 1will be described with reference to FIGS. 9, 10A, 10B and 10C.

FIG. 9 illustrates a flow chart of a method of forming a semiconductordevice according to an example embodiment of the inventive concept.FIGS. 10A, 10B, and 10C are cross-sectional views of a method of forminga semiconductor device according to an example embodiment of theinventive concept.

Referring to FIGS. 9 and 10A, an insulating structure 20 having anopening 21 is formed (S10). The insulating structure 20 includes aninsulating layer 20 a and an etch stop layer 20 b disposed on theinsulating layer 20 a. The insulating layer 20 a may for example beformed of a silicon oxide or a low-k dielectric having a dielectricconstant lower than that of the silicon oxide. The etch stop layer 20 bmay be formed of a material different from that forming the insulatinglayer 20 a, such as for example a silicon nitride. The insulating layer20 a and the etch stop layer 20 b may be formed of other materials. Theinsulating structure 20 may be formed on or over a substrate 10. Thesubstrate 10 may be a semiconductor substrate having a variety ofcomponents that may configure a semiconductor device. For example, thesubstrate 10 may be a semiconductor substrate including source/drainregions or a well contact region formed by doping a semiconductormaterial with an impurity.

A barrier material layer 49 is formed on the insulating structure 20 andon the substrate 10 within the opening 21 (S20). The barrier materiallayer 49 may be conformally formed on the insulating structure 20 havingthe opening 21. The forming of the barrier material layer 49 may includeforming a first barrier layer such as titanium (Ti) or the like, andforming a second barrier layer such as titanium nitride (TiN) or thelike on the first barrier layer.

In this specification, “forming conformally” may mean that acorresponding layer is formed to have a uniform thickness along a curveof a bottom or underlying structure.

Referring to FIGS. 9 and 10B, a nucleation material layer 59 is formedon the barrier material layer 49 by performing a first depositionprocess (S30). The first deposition process may be an ALD process usinga first reducing material, a second reducing material, and a sourcematerial. The first reducing material may be B₂H₄ gas, the secondreducing material may be SiH₄ gas or GeH₄ gas, and the source materialmay be WF₆ gas.

Referring to FIGS. 9 and 10C, a conductive material layer 69 is formedon the nucleation material layer 59 by performing a second depositionprocess using the nucleation material layer 59 as a seed (S40). Thesecond deposition process may be a CVD process using a third reducingmaterial and a source material. The third reducing material may bedifferent from the first and second reducing materials used in the firstdeposition process for forming the nucleation material layer 59. Forexample, the third reducing material may be H₂ gas. The source materialused in the second deposition process may be the same as the sourcematerial used in the first deposition process for forming the nucleationmaterial layer 59. Thus, as with the source material used in the firstdeposition process, the source material used in the second depositionprocess may for example be WF₆ gas.

Referring to FIGS. 1 and 9, a conductive structure 30 remaining in theopening 21 is formed by performing a planarizing process (S50). Theplanarizing process may include planarizing the conductive materiallayer 69, the nucleation material layer 59, and the barrier materiallayer 49 such as shown in FIG. 10C until a top surface of the insulatingstructure 20 is exposed. The planarizing process may be performed usinga chemical mechanical polishing (CMP) process. The planarizing processmay expose the insulating layer 20 a. Thus, the etch stop layer 20 bdisposed on the insulating layer 20 a may be removed during or after theplanarizing process. The conductive material layer 69, the nucleationmaterial layer 59, and the barrier material layer 49 are thus planarizedto respectively form conductive pattern 60, nucleation structure 50, andbarrier structure 40 such as shown in FIG. 1. Thus, the conductivestructure 30 remaining in the opening 21 may include the conductivepattern 60, the nucleation structure 50, and the barrier structure 40.

A portion of a top surface of the nucleation structure 50 may berecessed further than top surfaces of the conductive pattern 60 and thebarrier structure 40 by the planarizing process performed using the CMPprocess. Thus, the nucleation structure 50 may have a stepped topsurface 50 s formed using the CMP process. In particular, the polishingrate of the first nucleation layer 52 shown in FIG. 2 for example duringthe CMP process may be greater than the polishing rate of the secondnucleation layer 58 during the CMP process, resulting in the top surface50 s 1 of the first nucleation layer 52 being recessed further than thetop surface 50 s 2 of the second nucleation layer 58.

The nucleation structure 50 may be formed as one of the nucleationstructures 50 described with reference to FIGS. 2 and 5A through 5D. Asdescribed above, in order to form one of the nucleation structures 50described with reference to FIGS. 2 and 5A through 5D as describedabove, the nucleation material layer 59 of FIG. 10B may be formed byperforming the first deposition process as described with reference toFIGS. 9 and 10B. A method of forming the nucleation material layer 59 ofFIG. 10B by performing the first deposition process will be describedwith reference to FIG. 11.

FIG. 11 illustrates a flow chart of a method of forming a semiconductordevice according to an example embodiment of the inventive concept.

Referring first to FIGS. 9, 10B, and 11, the nucleation material layer59 of FIG. 10B may be formed by performing the first deposition process(S30). The first deposition process may proceed as follows.

A substrate is loaded into a process chamber (S32). The substrate may bea semiconductor substrate including the barrier material layer 49thereon as illustrated in FIG. 10A. The barrier material layer 49 (referto FIG. 10A) of the substrate may be in an exposed state. The processchamber may be part of typical ALD process equipment. Subsequently, thenucleation material layer 59 of FIG. 10B is formed on the substrate bysupplying a first reducing material, a second reducing material, and asource material to the process chamber (S34). The nucleation materiallayer 59 of FIG. 10B may be in direct contact with the barrier materiallayer 49. The substrate may be unloaded (S36).

The nucleation material layer 59 of FIG. 10B may be formed as one of thenucleation structures 50 described with reference to FIGS. 2 and 5Athrough 5D by the operation (S34) of forming the nucleation materiallayer 59 of FIG. 10B on the substrate by supplying the first reducingmaterial, the second reducing material, and the source material to theprocess chamber in the first deposition process. Hereinafter, variousexamples of the operation (S34) of forming the nucleation material layer59 of FIG. 10B as one of the nucleation structures 50 described withreference to FIGS. 2 and 5A through 5D will be described with referenceto FIGS. 12A through 12F.

FIGS. 12A through 12F illustrate gas pulsing diagrams of variousrespective examples of methods of forming a semiconductor deviceaccording to embodiments of the inventive concept.

The forming of the nucleation material layer 59 of FIG. 10B may includesupplying one of first and second reducing materials to a processchamber in a pulsed manner, and repeating one cycle in which a sourcematerial is supplied to the process chamber in a pulsed manner. During atime between the supplying of the first and second reducing materialsand the source material in the pulsed manner, purging may be performedin the process chamber. Thus, the one cycle may include supplying one ofthe first and second reducing materials in the pulsed manner, purgingthe supplied one of the first and second reducing materials, supplyingthe source material in the pulsed manner, and purging the suppliedsource material before a subsequent one cycle is performed. Hereinafter,the one cycle may also be understood as a unit process. Thus, the term“unit process” used below may also be replaced with the term “onecycle.”

In some example embodiments of the inventive concept, of the first andsecond reducing materials used in the process of forming the nucleationmaterial layer 59 of FIG. 10B, one reducing material, having relativelylow Gibbs free energy (AG) with respect to the source material may besupplied to the process chamber first, and the other reducing materialhaving relatively high Gibbs free energy (AG) with respect to the sourcematerial may be supplied to the process chamber last. In some exampleembodiments of the inventive concept, the one reducing material havingrelatively low Gibbs free energy (AG) with respect to the sourcematerial may be the first reducing material, and the other reducingmaterial having relatively high Gibbs free energy (AG) with respect tothe source material may be the second reducing material. Thus, the firstreducing material may have Gibbs free energy (AG) lower than that of thesecond reducing material, with respect to the source material. Forexample, the first reducing material may be B₂H₄ gas, the secondreducing material may be SiH₄ gas or GeH₄ gas, and the source materialmay be WF₆ gas.

The method of forming the nucleation material layer 59 of FIG. 10B asthe nucleation structure 50 described with reference to FIG. 2 will bedescribed with reference to FIGS. 2, 9, 10B, and 12A.

Referring to FIGS. 2, 9, 10B, and 12A, the forming of the nucleationmaterial layer 59 of FIG. 10B may include performing an initial unitprocess C_INI, performing an intermediate process C_M, and a final unitprocess C_F.

The initial unit process C_INI includes supplying a first reducingmaterial and a source material to the process chamber sequentially. Theinitial unit process C_INI may include purging during a time between thesupplies of the first reducing material and the source reducingmaterial, and purging after the supply of the source material in apulsed manner. Thus, the initial unit process C_INI includessequentially supplying the first reducing material to the processchamber for a period of time or in a pulsed manner, purging the suppliedfirst reducing material while stopping the supply of the first reducingmaterial, supplying the source material to the process chamber for aperiod of time or in a pulsed manner, and purging the supplied sourcematerial while stopping the supply of the source material.

A nucleation material formed using the initial unit process C_INI may bereferred to as a “first nucleation material”.

In an example embodiment of the inventive concept, the intermediateprocess C_M includes performing a plurality of intermediate unitprocesses C_Mb. Each of the intermediate unit processes C_Mb includessequentially supplying the first reducing material to the processchamber in a pulsed manner, purging the supplied first reducing materialwhile stopping the supply of the first reducing material, supplying thesource material to the process chamber in a pulsed manner, and purgingthe supplied source material while stopping the supply of the sourcematerial. The intermediate unit processes C_Mb of the intermediateprocess C_M may be performed under the same process conditions as thoseof the initial unit process C_INI. Thus, the intermediate unit processesC_Mb may form the first nucleation material as in the initial unitprocess C_INI.

In this specification, the initial unit process C_INI may be referred toas an “initial cycle,” the intermediate unit processes C_Mb may bereferred to as “intermediate cycles,” and the final unit process C_F maybe referred to as a “final cycle.”

The final unit process C_F includes sequentially supplying the secondreducing material to the process chamber for a period of time or in apulsed manner, purging the supplied second reducing material whilestopping the supply of the second reducing material, supplying thesource material to the process chamber for a period of time or in apulsed manner, and purging the supplied source material while stoppingthe supply of the source material. The first reducing material mayinclude B₂H₄ gas. The second reducing material may include SiH₄ gas orGeH₄ gas. The source material may include WF₆ gas. The final unitprocess C_F may form the second nucleation material.

Of the first and second reducing materials, the first reducing materialhaving relatively low Gibbs free energy (ΔG) with respect to the sourcematerial is supplied first to the process chamber to form first thefirst nucleation material, thereby significantly reducing or preventinga volcano effect that may occur due to volatile TiF₃ formed by areaction between F⁻ of the WF₆ gas and titanium (Ti) of the barrierstructure 40 formed of a titanium (Ti)/titanium nitride (TiN) material.The first nucleation material may be less influenced by a material typeor characteristic of the barrier structure 40 than the second nucleationmaterial, and thus the first nucleation material may be deposited orformed on the barrier structure 40 to have a thickness that is moreuniform than that of the second nucleation material. That is, althoughthe second nucleation material is not deposited on the barrier structure40 and does not have a thickness that is more uniform than that of thefirst nucleation material, the second nucleation material may bedeposited on the first nucleation material to have a uniform thickness.

The first nucleation material may be amorphous, and the secondnucleation material may be crystalline. The conductive material layer 69of FIG. 10C formed after forming the nucleation material layer 59 may becrystalline and may have a grain size greater than that of the secondnucleation material of the nucleation material layer 59, as describedwith reference to the grain size in FIG. 3.

The nucleation material layer 59 may include a first impurity elementand a second impurity element. As described with reference to thedistribution characteristics of the first and second impurity elementsin FIG. 4, in the nucleation material layer 59, the concentration of thefirst impurity element in the first nucleation material may be higherthan the concentration of the first impurity element in the secondnucleation material, and the concentration of the second impurityelement in the second nucleation material may be higher than theconcentration of the second impurity element in the first nucleationmaterial. The first impurity element may be boron (B), and the secondimpurity element may be fluorine (F).

In another example embodiment of the inventive concept, the intermediateunit processes C_Mb of the intermediate process C_M immediately beforeperforming the final unit process C_F is performed under the sameprocess conditions as those of the final unit process C_F. Thus, asillustrated in FIG. 12B, the intermediate process C_M includessequentially first intermediate unit processes C_Mb performed under thesame process conditions as those of the initial unit process C_INI, anda second intermediate unit process C_Ms performed under the same processconditions as those of the final unit process C_F. More generally, theintermediate process C_M may be characterized as including a firstintermediate unit process (such as C_Mb) that includes supplying one ofthe first reducing material and the second reducing material, and thesource material, to the process chamber sequentially; and a secondintermediate unit process (such as C_Ms) that includes supplying another one of the first reducing material and the second reducingmaterial, and the source material, to the process chamber sequentially.

The thickness of the first nucleation material in the nucleationmaterial layer 59 may be determined according to the number ofrepetitions of the first intermediate unit processes C_Mb in theintermediate process C_M performed under the same process conditions asthose of the initial unit process C_INI. The thickness of the secondnucleation material in the nucleation material layer 59 may also bedetermined according to the number of repetitions of the secondintermediate unit process C_Ms in the intermediate process C_M performedunder the same process conditions as those of the final unit processC_F. In an example embodiment, the first nucleation material may have athickness greater than that of the second nucleation material similar asshown in FIG. 2 wherein the thickness t1 of the first nucleation layer52 is greater than the thickness t2 of the second nucleation layer 58.

The first nucleation material may be formed as the first nucleationlayer 52 of FIG. 2, and the second nucleation material may be formed asthe second nucleation layer 58 of FIG. 2. Thus, the first and secondnucleation materials of the first and second nucleation layers 52 and 58have been described with reference to FIGS. 1 and 2, and thus detaileddescriptions thereof will be omitted hereinafter.

An example of a method of forming the nucleation structure 50 describedwith reference to FIG. 5A will be described with reference to FIGS. 5A,9, 10B, and 12C.

Referring to FIGS. 5A, 9, 10B, and 12C, the forming of the nucleationmaterial layer 59 of FIG. 10B includes performing an initial unitprocess C_INI and a final unit process C_F the same as those illustratedin FIG. 12A.

An intermediate process C_M is performed between the initial unitprocess C_INI and the final unit process C_F. The intermediate processC_M includes performing sequentially the second intermediate unitprocess C_Ms and the first intermediate unit process C_Mb such asdescribed with respect to FIG. 12B. The second intermediate unit processC_Ms may be performed under the same process conditions as those of thefinal unit process C_F, and the first intermediate unit process C_Mb maybe performed under the same process conditions as those of the initialunit process C_INI. Thus, the second intermediate unit process C_Ms andthe final unit process C_F may form the second nucleation material(corresponding to the nucleation layers 54 and 58 shown in FIG. 5A forexample), and the first intermediate unit process C_Mb and the initialunit process C_INI may form the first nucleation material (correspondingto the nucleation layers 52 a and 56 shown in FIG. 5A for example).Thus, the first and second nucleation materials in the nucleationmaterial layer 59 of FIG. 10B may be formed alternately and repeatedly.The nucleation material layer 59 of FIG. 10B may be formed as thenucleation structure 50 illustrated in FIG. 5A.

In a modified example, in order to form the nucleation structure 50illustrated in FIG. 5B, the number of repetitions of the firstintermediate unit processes C_Mb in the intermediate process C_M may beincreased, as illustrated in FIG. 12D. Thus, the nucleation structure 50of FIG. 5B may be formed including the first nucleation layer 52 a ofFIG. 5B, the first intermediate nucleation layer 54 of FIG. 5B, thesecond intermediate nucleation layer 56′ formed to have an increasedthickness by increasing the number of repetitions of the firstintermediate unit processes C_Mb, and the second nucleation layer 58 ofFIG. 5B.

In a modified example, in order to form the nucleation structure 50illustrated in FIG. 5C, the number of repetitions of the secondintermediate unit processes C_Ms in the intermediate process C_M may beincreased, as illustrated in FIG. 12E. Thus, the increase in the numberof repetitions of the second intermediate unit processes C_Ms asillustrated in FIG. 12E results in the thickness of the secondnucleation material formed using the intermediate process C_M to beincreased. Thus, the nucleation structure 50 of FIG. 5C may be formed,including the first nucleation layer 52 a of FIG. 5C, the firstintermediate nucleation layer 54′ of FIG. 5C formed to have an increasedthickness by increasing the number of repetitions of the secondintermediate unit processes C_Ms, the second intermediate nucleationlayer 56 of FIG. 5C, and the second nucleation layer 58 of FIG. 5C.

In a modified example, in order to form the nucleation structure 50illustrated in FIG. 5D, the number of repetitions of the secondintermediate unit processes C_Ms and the number of repetitions of thefirst intermediate unit processes C_Mb in the intermediate process C_Mmay be increased, as illustrated in FIG. 12F. Thus, the nucleationstructure 50 of FIG. 5D may be formed, including the first nucleationlayer 52 a of FIG. 5D, the first intermediate nucleation layer 54′ ofFIG. 5D formed to have an increased thickness by increasing the numberof repetitions of the second intermediate unit processes C_Ms, thesecond intermediate nucleation layer 56′ of FIG. 5D formed to have anincreased thickness by increasing the number of repetitions of the firstintermediate unit processes C_Mb, and the second nucleation layer 58 ofFIG. 5D.

As described above, the conductive structure 30 may include theconductive pattern 60 formed of a bulk tungsten (W) material, thebarrier structure 40 covering the bottom (lowermost) surface and thelateral surfaces of the conductive pattern 60, and the nucleationstructure 50 disposed between the barrier structure 40 and theconductive pattern 60.

The nucleation structure 50 may include the first nucleation layer 52formed of the first nucleation material, and the second nucleation layer58 formed of the second nucleation material. The first nucleationmaterial contacting the barrier structure 40 may significantly reduce orprevent a volcano effect that may occur in a contact plug or the like.The second nucleation material contacting the conductive pattern 60 maycover an upper lateral surface of the conductive pattern 60 to thusprotect the conductive pattern 60 from a planarizing process such as aCMP used to form the conductive structure 30.

In further embodiments of the inventive concept, the nucleationstructure 50 may include any number (plurality) of intermediatenucleation layers (such as first and second intermediate nucleationlayers 54 and 56 in FIG. 5A) between the first nucleation layer 52 andthe second nucleation layer 58. At least one of the intermediatenucleation layers may include (be formed of) the second nucleationmaterial previously described, and a remainder of the intermediatenucleation materials may include (be formed of) the first nucleationmaterial previously described. In further embodiments of the inventiveconcept, at least one of the intermediate nucleation layers (such asfirst and second intermediate nucleation layers 54 and 56 in FIG. 5A)and the first nucleation layer 52 may include (be formed of) the (same)first nucleation material previously described, and a remainder of theintermediate nucleation layers and the second nucleation material 58 mayinclude (be formed of) the (same) second nucleation material previouslydescribed.

As set forth above, according to example embodiments of the inventiveconcept, a semiconductor device including a conductive structure havinga nucleation structure may be provided. The occurrence of defects in theconductive structure may be significantly reduced or suppressed byforming the nucleation structure using first and second nucleationmaterials having different characteristics. Further, electricalcharacteristics of the conductive structure may be improved. Thus, theoccurrence of defects in the semiconductor device may be significantlyreduced or suppressed, and performance of the semiconductor device maybe improved.

The foregoing is illustrative of embodiments of the inventive conceptwith reference to the accompanying drawings. Although a number ofembodiments have been described, those of ordinary skill in the art willreadily understand that many modifications are possible in embodimentswithout materially departing from the novel teachings and advantages.Therefore, it is to be understood that the foregoing is illustrative ofvarious embodiments and is not to be construed as limited to thespecific embodiments disclosed.

What is claimed is:
 1. A semiconductor device comprising: a substrate; aplurality of fins disposed on the substrate and including a first finand a second fin; an isolation layer disposed on the substrate anddisposed between the first fin and the second fin; a gate disposed onthe plurality of fins and on the isolation layer, and including a gateelectrode and a gate dielectric covering side surfaces and a bottomsurface of the gate electrode; a plurality of source/drains including afirst source/drain disposed on the first fin and a second source/draindisposed on the second fin; and a contact plug disposed on the pluralityof source/drains and including a first layer and a second layer coveringside surfaces of the first layer, wherein the second layer includes afirst portion covering the side surfaces of the first layer, and asecond portion covering side surfaces of the first portion, the firstportion of the second layer of the contact plug is disposed between thefirst layer of the contact plug and the second portion of the secondlayer of the contact plug, and a top surface of the second portion ofthe second layer of the contact plug is recessed.
 2. The semiconductordevice of claim 1, wherein the contact plug includes a third layercovering side surfaces of the second layer.
 3. The semiconductor deviceof claim 1, wherein the second layer of the contact plug includestungsten (W).
 4. The semiconductor device of claim 1, wherein athickness of the second portion of the second layer of the contact plugis different from a thickness of the first portion of the second layerof the contact plug.
 5. The semiconductor device of claim 1, wherein athickness of the second portion of the second layer of the contact plugis the same as a thickness of the first portion of the second layer ofthe contact plug.
 6. The semiconductor device of claim 1, wherein thesecond layer includes a third portion covering side surfaces of thesecond portion, a thickness of the second portion of the second layer isdifferent from a thickness of the third portion of the second layer, andthe first portion and the third portion of the second layer of thecontact plug are formed of the same material.
 7. The semiconductordevice of claim 1, wherein the second layer includes a third portioncovering side surfaces of the second portion, a thickness of the secondportion of the second layer is the same as a thickness of the thirdportion of the second layer, and a top surface of the third portion ofthe second layer of the contact plug is recessed.
 8. The semiconductordevice of claim 1, wherein the second layer includes a third portioncovering side surfaces of the second portion and a fourth portioncovering side surfaces of the third portion, a top surface of the thirdportion of the second layer of the contact plug and a top surface of thefourth portion of the second layer of the contact plug are recessed, thefirst portion and the third portion of the second layer of the contactplug are formed of the same material, and the second portion and thefourth portion of the second layer of the contact plug are formed of thesame material.
 9. A semiconductor device comprising: a substrate; aplurality of fins disposed on the substrate and including a first finand a second fin; an isolation layer disposed on the substrate anddisposed between the first fin and the second fin; a gate disposed onthe plurality of fins and on the isolation layer, and including a gateelectrode and a gate dielectric covering side surfaces and a bottomsurface of the gate electrode; a plurality of source/drains including afirst source/drain disposed on the first fin and a second source/draindisposed on the second fin; and a contact plug disposed on the pluralityof source/drains and including a first layer and a second layer coveringside surfaces of the first layer, wherein the second layer includes afirst portion, a second portion covering side surfaces of the firstportion, and a third portion covering side surfaces of the secondportion, a thickness of the second portion of the second layer of thecontact plug is different from a thickness of the third portion of thesecond layer of the contact plug, and a top surface of the secondportion of the second layer of the contact plug is recessed.
 10. Thesemiconductor device of claim 9, wherein the thickness of the secondportion of the second layer of the contact plug is greater than thethickness of the third portion of the second layer of the contact plug.11. The semiconductor device of claim 9, wherein the thickness of thesecond portion of the second layer of the contact plug is less than thethickness of the third portion of the second layer of the contact plug.12. The semiconductor device of claim 9, wherein the thickness of thesecond portion of the second layer of the contact plug is the same as athickness of the first portion of the second layer of the contact plug.13. The semiconductor device of claim 9, wherein the thickness of thesecond portion of the second layer of the contact plug is different froma thickness of the first portion of the second layer of the contactplug.
 14. The semiconductor device of claim 9, wherein the secondportion of the second layer of the contact plug is formed of a materialdifferent from a material of which the third portion of the second layerof the contact plug is formed.
 15. The semiconductor device of claim 9,wherein the second layer of the contact plug includes tungsten (W). 16.The semiconductor device of claim 9, wherein a top surface of the firstportion of the second layer of the contact plug is higher than the topsurface of the second portion of the second layer of the contact plug.17. The semiconductor device of claim 9, wherein a top surface of thethird portion of the second layer of the contact plug is higher than thetop surface of the second portion of the second layer of the contactplug.
 18. A semiconductor device comprising: a substrate; a plurality offins disposed on the substrate and including a first fin and a secondfin; an isolation layer disposed on the substrate and disposed betweenthe first fin and the second fin; a gate disposed on the plurality offins and on the isolation layer, and including a gate electrode and agate dielectric covering side surfaces and a bottom surface of the gateelectrode; a plurality of source/drains including a first source/draindisposed on the first fin and a second source/drain disposed on thesecond fin; and a contact plug disposed on the plurality ofsource/drains and including a first layer, a second layer covering sidesurfaces of the first layer, and a third layer covering side surfaces ofthe second layer, wherein the second layer includes a first portion anda second portion covering side surfaces of the first portion, athickness of the second portion of the second layer of the contact plugis different from a thickness of the first portion of the second layerof the contact plug, and a top surface of the second portion of thesecond layer of the contact plug is recessed.
 19. The semiconductordevice of claim 18, wherein the second layer further includes a thirdportion covering side surfaces of the second portion, and a fourthportion covering side surfaces of the third portion, and a top surfaceof the third portion of the second layer of the contact plug and a topsurface of the fourth portion of the second layer of the contact plugare recessed.
 20. The semiconductor device of claim 18, wherein thesecond portion of the second layer of the contact plug is formed of amaterial different from a material of which the first portion of thesecond layer of the contact plug is formed.